This project is concerned with the structure, function, chemistry and development of synapses within the vertebrate retina. The processing of visual information within the retina depends on, and derives from, the synaptic interactions occurring within the retinal plexiform layers. An understanding of these synaptic junctions is prerequisite for an understanding of retinal function. For the next five years of the project, five sub-projects are planned: 1) Synaptic organization of physiological subtypes of ganglion cells. The synaptic contacts made onto catfish and rabbit ganglion cells, stained intracellularly with horseradish peroxidase, will be determined by electron microscopy. 2) Synaptic organization of pharmacological subtypes of retinal elements. The synapses made by an onto identified retinal elements in fish and rabbit, stained with transmitter-specific monoclonal antibodies, will be examined by electron microscopy. 3) The production and characterization of monoclonal antibodies against retinal neurons. Monoclonal antibodies specific to the surfaces of fish retinal cells will be produced and the antibodies used to probe for functional groups on retinal cell membranes. 4) Isolation and biochemical characterization of horizontal cell gap junctions. Gap junctional membranes will be isolated from the white perch retina, the junctional proteins extracted and separated, and the possible phosphorylation of the junctional proteins by cyclic AMP dependent kinase tested. 5) Formation of synapses between fish retinal cells in culture. The factors underlying retinal cell longevity, process growth and synaptogenesis in culture will be studied.